Advanced Laguerre Tessellation for the Reconstruction of Ceramic Foams and Prediction of Transport Properties

Stiapis, Christos S.; Skouras, E. D.; Burganos, Vasilis N.

doi:10.3390/ma12071137

Cited by 7 publications

(8 citation statements)

References 44 publications

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“…The pore size distribution is considered a significant structural parameter despite the total porosity [36]. Voronoi tessellation allows individuating for each core of the random distribution, the regions of space by considering the points that are less distant from each core than the others.…”

Section: Methodsmentioning

confidence: 99%

Design and Thermal Comparison of Random Structures Realized by Indirect Additive Manufacturing

Almonti

Ucciardello

2019

Materials

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Additive manufacturing (AM) processes are used to fabricate three-dimensional complex geometries. There are several technologies that use laser or electron beam over metal powder beds. However, the direct AM processes have inconveniences such as specific set of materials, high thermal stress traced, high local energy absorbed, poor surface finish, anisotropic properties, high cost of material powder, and manufacturing with high-power beams. In this paper, an alternative process was developed. An indirect additive manufacturing (I-AM) combining a 3D print of castable resin and metal casting in order to obtain a cellular structure similar in shape to commercial metal foams but completely definable as design features was developed. Design of the cellular structure was made by the graphical algorithm editor Grasshopper®. Designed structures were realized by a lost-wax casting process and compared with commercial foam specimens by a system designed for this work. The designed metal foams showed a performance superior to that of commercial metal foam; in particular, the heat thermal coefficient of designed metal foams in the better case was 870 W/m2·K, almost doubled in comparison with the commercial foam tested in this work.

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Section: Methodsmentioning

confidence: 99%

Design and Thermal Comparison of Random Structures Realized by Indirect Additive Manufacturing

Almonti

Ucciardello

2019

Materials

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“…Errors resulting from → r ij ≥ R i + R j do not affect the stability of the algorithm. In order to deal with the floating point precision problem, the algorithm that was proposed by Bannerman et al [18] is implemented. In this algorithm, an overlap function, F HS , is used at any time step, defined as the left-hand-side of Equations (1) and shown in Equation (2),…”

Section: Sphere Collisionsmentioning

confidence: 99%

“…According to observations by Hutter et al [16], the branch thickness, as well as the branch shape, reportedly affect the mass transport properties of the foam to a large extent. Bracconi et al [17] and Stiapis et al [18] attempted to remediate those shortcomings by introducing different branch variation algorithms that shape the strut thickness along the length of branches, greatly improving the description of the solid domain and showing notable agreement with the experimental data. However, these branch variation methods require a predefined arrangement either of points or of non-overlapping spheres, parameters that greatly affect the outcome of the tessellation process.…”

Section: Introductionmentioning

confidence: 99%

“…Effective transport properties can then be extracted accurately using computational treatment only, thus avoiding exhaustive experimentation. The distinctive advantage of this reconstruction algorithm over other algorithms found in the literature [17,18] is that this algorithm can digitally reconstruct foam structures where each pore cell may be interconnected with others via multiple pore windows and other pore cells. Moreover, this algorithm can be used in order to predict the 3D porosity as a function of the wall thickness of the spherical caps (a quantity that can be easily extracted from Scanning Electron Microscopy (SEM) images).…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Digital Reconstruction of Ti2AlC Ceramic Foams Produced by the Gelcast Method

2019

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A digital reconstruction technique is presented that generates three-dimensional (3D) digital representations of ceramic foams created by the foam-gelcasting technique. The reconstruction process uses information that is directly extracted from Scanning Electron Microscopy (SEM) images and offers a 3D representation of the physical sample accounting for the typically large pore cavities and interconnecting windows that are formed during the preparation process. Contrary to typical tessellation-based foam treatments, a spherical representation of the pores and the pore windows of the foams is assumed and a novel hybrid algorithm that combines a variation of Lubachevsky-type and Random Close Packing of Hard Spheres (RCPHS) algorithms has been developed to obtain near-optimum solutions to the packing problem of the spheres that represent the pores. Numerical simulations are performed directly on the 3D reconstructed foams to determine their gas permeability. The model predictions are compared with experimental gas permeability data that were obtained for the physical samples. The pore wall thickness can be treated as the single fitting parameter in the entire reconstruction process, although it is shown that images of sufficient resolution could eliminate the need even for that. The foams that are produced by this method yield quantitatively similar pressure drops with experiments for various superficial velocity values, with a very small deviation in the range of 1.7–2.8%. The proposed methodology could be utilized for the prediction of the permeability and transport properties of complex foamy porous structures, similar to the gelcast-type of foams, from a single SEM image of the foam sample without resorting to serial tomography or other structural information, thus saving considerable time and effort from experimental work.

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“…For a randomly formed heterogeneous material with n phases, a general ETC, Γeff is:Γeff=normalf(Γ1, Γ2, …, Γn; ϕ1, ϕ2, …, ϕn; Ω∗) where subscript of variables denotes its respective phase, Γ is the proportionality constant for that phase, ϕ is the phase volume fraction and Ω∗ is the microstructural information of the domain [2]. The review of the literature showed that there are different mathematical relationships to determine ETC’s [5,6,7]. However, a powerful technique to compute ETC is through a microstructural reconstruction, a differential equations model of the transport phenomenon and its numerical solution [8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Effect of An Image Resolution Change on the Effective Transport Coefficient of Heterogeneous Materials

et al. 2019

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Electrochemical electrodes comprise multiple phenomena at different scales. Several works have tried to model such phenomena using statistical techniques. This paper proposes a novel process to work with reduced size images to reconstruct microstructures with the Simulated Annealing method. Later, using the Finite Volume Method, it is verified the effect of the image resolution on the effective transport coefficient (ETC). The method can be applied to synthetic images or images from the Scanning Electron Microscope. The first stage consists of obtaining the image of minimum size, which contains at least 98% of the statistical information of the original image, allowing an equivalent statistical study. The image size reduction was made by applying an iterative decimation over the image using the normalized coarseness to compare the amount of information contained at each step. Representative improvements, especially in processing time, are achieved by reducing the size of the reconstructed microstructures without affecting their statistical behavior. The process ends computing the conduction efficiency from the microstructures. The simulation results, obtained from two kinds of images from different materials, demonstrate the effectivity of the proposed approach. It is important to remark that the controlled decimation allows a reduction of the processor and memory use during the reconstruction and ETC computation of electrodes.

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Advanced Laguerre Tessellation for the Reconstruction of Ceramic Foams and Prediction of Transport Properties

Cited by 7 publications

References 44 publications

Design and Thermal Comparison of Random Structures Realized by Indirect Additive Manufacturing

Design and Thermal Comparison of Random Structures Realized by Indirect Additive Manufacturing

Three-Dimensional Digital Reconstruction of Ti2AlC Ceramic Foams Produced by the Gelcast Method

Effect of An Image Resolution Change on the Effective Transport Coefficient of Heterogeneous Materials

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